The present invention relates to a magnetic levitated motor in which a rotor is magnetically supported in non-contact and rotatable manner.
A magnetic bearing has been used for supporting a rotary member in non-contact manner. A radial type magnetic levitated motor is proposed which functions as a magnetic bearing and a motor. The magnetic levitation motor is advantageous in that it is capable of simultaneously exercising the rotor torque generation and the position control, but it is disadvantageous in that the stator structure and the control circuit are complex.
A magnetic levitated motor disclosed in Japanese Patent Publication No. 6-269144A includes a stator having magnetic poles formed on the inner face thereof, each magnetic pole being wound by a single pole coil a rotor made of permanent magnet, the rotor having M number of magnetic poles, which are confronted with the inner wall of the stator with a gap therebetween, and a controller for feeding current for generating a revolving magnetic field having (M.+-.2) number of poles along the inner face of the stator and current for rotating the rotor to the coils of the stator, wherein a magnetic levitational force is developed through the magnetic interaction between the revolving magnetic field having (M.+-.2) number of poles along the inner face of the stator and the permanent magnet of the rotor. The current for rotating the rotor is superposed on the current for developing the levitational force and the resultant is fed to the stator. As a result, the rotor is magnetically levitated and rotated.
The related magnetic levitated motor requires a complicated magnetic flux distribution for the stator. Therefore, its structure is complex, and complicated levitational force control is required. Accordingly, there is a limit in increasing the motor speed. Further its face is covered with the permanent magnet, so that a levitational force is weak, and its efficiency is unsatisfactory.